Flat panel lighting device and retrofit kit

ABSTRACT

The present application is directed to a light fixture and associated retrofit lighting kit that includes a substantially flat light emitting diode panel. The light fixture can be employed in a variety of applications, including installation as a standalone fixture, a replacement for a fluorescent lighting unit and as a retrofit lighting kit to be used in connection with an existing fluorescent lighting unit.

RELATED APPLICATION DATA

The present application claims benefit of U.S. Provisional App. No.61/487,253, filed May 17, 2011, which is incorporated by reference inits entirety. The present application also claims benefit of U.S.Provisional App. No. 61/579,472, filed Dec. 22, 2011, which isincorporated by reference in its entirety.

FIELD OF INVENTION

Present invention relates generally to lighting assemblies, and moreparticularly to a versatile, substantially flat panel light emittingdiode lighting assembly and retrofit lighting kit.

BACKGROUND

Lighting systems incorporating ceiling-mounted lighting fixtures orluminaires are routinely used to illuminate commercial floor space andobjects residing on the floor space within the illuminated area.Luminaires generally consist of an assembly of components, such aslamps, ballasts, and reflectors, which cooperate to produce and directlight. Luminaires that incorporate fluorescent lamps are the mostcommonly used commercial light sources due to their relatively highefficiency, diffuse light distribution characteristics, and longoperating life.

Fluorescent lamps are long tubes that contain mercury and argon gas.Electrodes sealed into each end of a tube allow the lamp to conduct anelectric current, thereby emitting ultra-violet radiation. The tube of afluorescent lamp is a glass envelope. The inside surface of the tube iscoated with a phosphor that provides visible illumination when excitedby ultra-violet radiation. The phosphor, or fluorescent coating, may beharmful to a person's eyes. The glass envelope is infamous for itsability to shatter and blanket an area with sharp glass. Theneurological toxicities associated with mercury exposure are welldocumented. Additionally, only a portion of the radiation produced by afluorescent lamp is ever converted into visible light. As withincandescent light bulbs, the excess radiation produces heat.Collectively, the heat generated by these lamps places a tremendousburden on the air conditioning system of a building, especially duringthe summer months in warmer climates.

Many conventional fluorescent lighting fixtures are adapted for recessedmounting in a suspended ceiling, in which the lighting fixtures havebulky box enclosures or troffers supported by adjacent pairs of T-barscomprising the support structure of the ceiling. In addition to housingand supporting the other components of the lighting fixture, the trofferprovides a fire protection enclosure.

Over the lifetime of a commercial lighting system, the expendituresassociated with operating and maintaining that system are significant.As lighting fixtures age and deteriorate, the light-emitting abilitydegrades and the light output per unit of consumed electrical energy issignificantly reduced. Modern ballasts, lamps and reflectors areavailable that would significantly enhance the light-emitting ability ofthe lighting system and also significantly enhance the energy efficiencyby reducing the power consumption. As a result, the light output couldbe increased while simultaneously reducing the associated energy costs.Thus, it is desirable to replace obsolete lighting fixtures withlighting fixtures that incorporate modern ballasts, lamps and lampsockets to hold the lamps, and reflectors.

Existing lighting fixtures of commercial light systems cannot be easilyupgraded to replace obsolete lighting fixtures with lighting fixturesthat incorporate modern components, or refurbished with moderncomponents to reverse the effects of deterioration. Conventionalfluorescent lighting fixtures and available retrofitting kits areunsatisfactory for upgrading existing lighting systems because, amongother things, the existing lighting fixtures must first be removed or,at the least, significantly modified by removing certain components fromthe existing lighting fixtures before the upgrade can be performed.Retrofitting with conventional fluorescent luminaires or availableretrofitting kits is a labor-intensive and lengthy process thatsignificantly disrupts commercial operations during the retrofitprocess. Furthermore, the removed lighting fixtures or componentsgenerate a waste stream for disposal or recycling. Disposal posessignificant environmental concerns from hazardous or toxic substances inthe removed components, such as mercury in the fluorescent lamps andchemicals including polychlorinated biphenyls (commonly referred to asPCB's) in the ballasts.

SUMMARY OF INVENTION

The present application is directed to a light fixture including asubstantially flat light emitting diode (LED) panel and an associatedretrofit lighting kit and retrofitting method. The light fixture andassociated retrofit kit are configured to provide an extremely thinlighting device with great versatility and simplicity of installationfor retrofit applications.

One aspect of the disclosed technology relates to a method ofretrofitting a fluorescent housing unit, the fluorescent housing unithaving an upper extent and a lower extent, the lower extent having aperimeter of a given shape and size. The method includes providing asubstantially flat light emitting diode (LED) panel, the substantiallyflat LED panel having a shape and size of approximately the given shapeand size of the perimeter of the lower extent of the fluorescent housingunit; electrically coupling the LED panel to a power supply associatedwith the fluorescent housing unit; and mounting the substantially flatLED panel to the fluorescent housing unit.

According to one feature, the substantially flat LED panel includes aframe having a shape and size of approximately the given shape and sizeof the perimeter of the lower extent of the fluorescent housing unit.

According to one feature, mounting includes mounting the substantiallyflat LED panel over the perimeter of the fluorescent housing unit.

According to one feature, mounting includes mounting the substantiallyflat LED panel within the perimeter of the lower extent of thefluorescent housing unit.

According to one feature, mounting includes hingedly mounting thesubstantially flat LED panel to the lower extent of the fluorescenthousing unit.

According to one feature, the fluorescent housing unit includes a coverhingedly connected to a body, the cover including a diffuser and/or alens, wherein mounting includes removing the diffuser and/or lens fromthe cover and mounting the substantially flat LED panel to the cover,such that the substantially flat LED panel is hingedly mounted to thebody of the fluorescent housing unit via the cover.

According to one feature, the cover defines a channel around a perimeterof the cover, the channel having a thickness, wherein the substantiallyflat LED panel has a thickness approximately equal to the thickness ofthe channel around the perimeter of the cover.

According to one feature, the perimeter of the lower extent offluorescent housing unit includes a channel having a thickness, whereinthe substantially flat LED panel has a thickness approximately equal tothe thickness of the channel around the perimeter of the lower extent ofthe fluorescent housing unit.

According to one feature, the fluorescent housing unit includes areflector grid connected to a body, wherein mounting includes removingthe reflector grid and mounting the substantially flat LED panel to thelower extent of the body of the fluorescent housing unit.

According to one feature, the fluorescent housing unit includes areflector grid connected to a body, wherein mounting includes removingthe reflector grid and mounting the substantially flat LED panel to thebody of the fluorescent housing unit and replacing the reflector gridsuch that the substantially flat LED panel is positioned above thereflector grid.

According to one feature, electrically coupling includes removing aballast associated with the fluorescent housing unit and electricallycoupling the substantially flat LED panel to the power supply via ablock transformer.

According to one feature, electrically coupling includes electricallycoupling the substantially flat LED panel to the power supply via one ormore fluorescent light sockets associated with the fluorescent housingunit.

According to one feature, the substantially flat LED panel includes oneor more connectors configured to electrically connect with thefluorescent light sockets associated with the fluorescent housing unit.

According to one feature, electrically coupling includes electricallycoupling the substantially flat LED panel to a ballast associated withthe fluorescent housing unit.

According to one feature, electrically coupling includes electricallycoupling the substantially flat LED panel to a ballast associated withthe fluorescent housing unit via a transformer associated with thesubstantially flat LED panel.

According to one feature, electrically coupling includes electricallycoupling the substantially flat LED panel to the power supply via atransformer incorporated into the frame of the substantially flat LEDpanel.

According to one feature, the substantially flat LED panel is edge lit.

According to one feature, the substantially flat LED panel includes aplurality of LEDs disposed adjacent at least one edge of the frame.

According to one feature, the frame is rectangular and the substantiallyflat LED panel includes an array of LEDs incorporated into at least twosides of the frame.

According to one feature, the substantially flat LED panel includes anoptically-transmissive panel; an array of LEDs disposed adjacent atleast one edge of the frame and the optically transmissive panel; adiffuser film disposed below the optically-transmissive panel; abrightness enhancement film (BEF) disposed above theoptically-transmissive panel; and a reflector disposed above the BEF.

Another aspect of the disclosed technology relates to a lighting kitadapted for installation into a fluorescent lighting unit, thefluorescent lighting unit including a housing unit, a fluorescentsocket, and a ballast disposed within the housing unit, the housing unithaving an upper extent and a lower extent, the lower extent having aperimeter of a given shape and size. The lighting kit includes asubstantially flat light emitting diode (LED) panel having a shape andsize of approximately the given shape and size of the perimeter of thelower extent of the housing unit; power circuitry configured toelectrically couple the substantially flat LED panel to a power supply;and at least one engagement member configured to couple thesubstantially flat LED panel to the housing unit of the fluorescentlighting unit.

Another aspect of the disclosed technology relates to a light fixtureincluding a frame; a substantially flat light emitting diode (LED) paneldisposed within the frame; and power circuitry disposed within the frameor adjacent the frame, the power circuitry being configured toelectrically couple the substantially flat LED panel to an externalpower supply.

According to one feature, the substantially flat LED panel includes aplurality of LEDs disposed adjacent at least one edge of the frame.

According to one feature, the frame is rectangular and the substantiallyflat LED panel includes an array of LEDs incorporated into at least twosides of the frame.

According to one feature, the substantially flat LED panel includes anoptically-transmissive panel; an array of LEDs disposed adjacent atleast one edge of the frame and the optically transmissive panel; adiffuser film disposed below the optically-transmissive panel; abrightness enhancement film (BEF) disposed above theoptically-transmissive panel; and a reflector disposed above the BEF.

According to one feature, the light fixture includes at least onemounting member configured to mount the frame to a substantiallyvertical support surface.

According to one feature, the substantially vertical support surface isa wall.

According to one feature, the light fixture includes at least onemounting member configured to mount the frame to a substantiallyhorizontal support surface.

According to one feature, the light fixture includes at least onemounting member configured to mount the frame under a substantiallyhorizontal support surface.

According to one feature, the substantially horizontal support surfaceis a storage cabinet.

According to one feature, the substantially flat LED panel includes aplurality of white LEDs.

According to one feature, the substantially flat LED panel includes aplurality of colored LEDs, where the colored LEDs are configured tocooperate to produce white light when energized.

According to one feature, the light fixture includes control circuitryconfigured to selectively energize the colored LEDs to provide lightoutput of variable color temperature.

According to one feature, the colored LEDs include white LEDs with colorfilters.

According to one feature, the frame is rectangular and the substantiallyflat LED panel includes a light guide plate; a first array of LEDsincorporated into a first side of the frame adjacent a first side of thelight guide plate, the first array of LEDs emitting light focused alonga first direction; a second array of LEDs incorporated into a secondside of the frame adjacent a second side of the light guide plate, thesecond array of LEDs emitting light focused along a second directionthat is opposite the first direction; a first brightness enhancementfilm (BEF) positioned adjacent the light guide plate and configured tocollimate light emitted by the first array of LEDs; and a second BEFpositioned adjacent the first BEF and configured to collimate lightemitted by the second array of LEDs.

According to one feature, the substantially flat LED panel includes astrip of LEDs disposed adjacent at least one edge of the frame, thestrip of LEDs being removably coupled to the power circuitry via anelectrical connector.

According to one feature, the power circuitry comprises a transformer.

According to one feature, the power circuitry comprises a LED driverdisposed within the frame.

According to one feature, the power circuitry comprises a controllerconfigured to control the intensity of the light emitted by thesubstantially flat LED panel.

According to one feature, a lighting assembly comprising the lightfixture electrically coupled to a second light fixture, the second lightfixture comprising a frame and a substantially flat light emitting diode(LED) panel disposed within the frame, wherein the second light fixtureis electrically coupled to the first light fixture and configured toreceive power from the external power supply associated with the firstlight fixture.

Another aspect of the disclosed technology relates to a desk lamp thatincludes a base, at least one support coupled to the base, and asubstantially flat light emitting diode (LED) panel operatively coupledto the at least one support.

Another aspect of the disclosed technology relates to a light fixturethat includes a frame; and a substantially flat light emitting diode(LED) panel disposed within the frame; wherein the frame includes abottom assembly and a top assembly coupled to the bottom assembly, thebottom assembly and the top assembly cooperating to form a plurality ofchannels within the frame; and wherein the bottom assembly includes aback surface and a plurality of mounting tabs on the back surface,wherein the mounting tabs are movable between (i) a first unextendedposition where the mounting tabs are substantially co-planar with theback surface, (ii) a first extended position where the mounting tabsextend out at an angle of approximately 90 degrees relative to the backsurface, and (ii) a second extended position where the mounting tabsextend out at an angle of approximately 180 degrees relative to the backsurface.

According to one feature, the mounting tabs are integrally formed withthe back surface of the bottom assembly.

According to one feature, the mounting tabs are formed as a cut-out fromthe back surface of the bottom assembly.

According to one feature, the mounting tabs are operatively coupled tothe back surface of the bottom assembly.

According to one feature, the mounting tabs define an apertureconfigured to receive a fastener.

According to one feature, the light fixture is configured to be mountedto a flat surface by the mounting tabs.

Another aspect of the disclosed technology relates to a light fixturethat includes a frame; a substantially flat light emitting diode (LED)panel disposed within the frame; wherein the frame includes a bottomassembly and a top assembly coupled to the bottom assembly, the bottomassembly and the top assembly cooperating to form a plurality ofchannels within the frame; and a mounting member configured to beattached to a flat surface, wherein the mounting member includes aplurality of engagement members configured to engage the bottom assemblyof the frame.

According to one feature, the engagement members comprise a plurality ofJ-hooks configured to engage slots within outer edges of the bottomassembly.

According to one feature, the mounting member is configured toreleasably engage the bottom assembly of the frame through a slide-lockmechanism.

According to one feature, the mounting member defines a central apertureconfigured to cooperate with an external junction box.

According to one feature, the mounting member defines a central apertureconfigured to receive AC input wiring.

Another aspect of the disclosed technology relates to a light fixturethat includes a frame; a substantially flat light emitting diode (LED)panel disposed within the frame, wherein the frame includes a bottomassembly and a top assembly coupled to the bottom assembly, the bottomassembly and the top assembly cooperating to form a plurality ofchannels within the frame; power circuitry disposed within at least oneof the plurality of channels within the frame, the power circuitry beingconfigured to electrically couple the substantially flat LED panel to anexternal AC power supply; and a central wire-way disposed adjacent aback surface of the bottom assembly, wherein the central wire-way isconfigured to house wiring electrically coupled to the external AC powersupply.

According to one feature, the central wire-way is configured to routewiring between opposite edges of the frame.

According to one feature, the central wire-way is configured to routewiring electrically coupling the external AC power supply to powersupplies disposed within channels in opposite edges of the frame.

According to one feature, the central wire-way includes a back covercoupled to a back surface of the bottom assembly.

According to one feature, the back cover defines a central apertureconfigured to receive AC input wiring electrically coupled to theexternal AC power supply.

According to one feature, the central aperture is configured as aknockout hole.

Another aspect of the disclosed technology relates to a light fixturethat includes a frame; a substantially flat light emitting diode (LED)panel disposed within the frame, wherein the frame includes a bottomassembly and a top assembly coupled to the bottom assembly, the bottomassembly and the top assembly cooperating to form a plurality ofchannels within the frame; power circuitry disposed within at least oneof the plurality of channels within the frame, the power circuitry beingconfigured to electrically couple the substantially flat LED panel to anexternal AC power supply; and a wire compartment disposed within atleast one of the plurality of channels within the frame, wherein thewire compartment is configured to house wiring electrically coupled tothe external AC power supply.

According to one feature, the bottom assembly of the frame defines anaperture configured to receive AC input wiring from the external ACpower supply.

According to one feature, the light fixture includes a cover positionedover the aperture, the cover defining a central aperture configured toreceive AC input wiring electrically coupled to the external AC powersupply.

According to one feature, the central aperture is configured as aknockout hole.

According to one feature, at least one edge of the frame defines thewire compartment and a power supply compartment separate from the wirecompartment.

According to one feature, the light fixture includes a central wire-waydisposed adjacent a back surface of the bottom assembly, wherein thecentral wire-way is configured to route wiring between opposite edges ofthe frame.

According to one feature, the central wire-way is configured to routewiring from the wire compartment in one edge of the frame to theopposite edge of the frame.

These and further features of the present invention will be apparentwith reference to the following description and attached drawings. Inthe description and drawings, particular embodiments of the inventionhave been disclosed in detail as being indicative of some of the ways inwhich the principles of the invention may be employed, but it isunderstood that the invention is not limited correspondingly in scope.Rather, the invention includes all changes, modifications andequivalents coming within the spirit and terms of the claims appendedthereto.

Features that are described and/or illustrated with respect to oneembodiment may be used in the same way or in a similar way in one ormore other embodiments and/or in combination with or instead of thefeatures of the other embodiments.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference tothe following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present invention. Likewise, elementsand features depicted in one drawing may be combined with elements andfeatures depicted in additional drawings.

Moreover, in the drawings, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 1A is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 1B is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 2 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 3 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 4 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 5 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 6 is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 6A is a diagrammatic illustration of a substantially flat LED panelin accordance with one aspect of the disclosed technology;

FIG. 7 is a rear view of a substantially flat LED panel in accordancewith one aspect of the disclosed technology;

FIG. 8 shows a portion of a substantially flat LED panel in accordancewith one aspect of the disclosed technology;

FIG. 9 shows an exploded view of an optical stack of a substantiallyflat LED panel in accordance with one aspect of the disclosedtechnology;

FIG. 10 shows an exploded view of bottom frame assembly in accordancewith one aspect of the disclosed technology;

FIG. 11 is a bottom plan view of the bottom frame assembly of FIG. 10;

FIG. 12 shows a top frame assembly in accordance with one aspect of thedisclosed technology;

FIG. 13 is an enlarged view of an exemplary inside bracket shown in FIG.10;

FIG. 14 is an enlarged view of an exemplary inside bracket shown in FIG.10;

FIG. 15 shows an exemplary mounting tab in a first position inaccordance with one aspect of the disclosed technology;

FIG. 16 shows an exemplary mounting tab in a second position inaccordance with one aspect of the disclosed technology;

FIG. 17 shows an exemplary mounting tab in a third position inaccordance with one aspect of the disclosed technology;

FIG. 18 shows an exemplary mounting tab in a second position inaccordance with one aspect of the disclosed technology;

FIG. 19 shows an exemplary mounting tab in a third position inaccordance with one aspect of the disclosed technology;

FIG. 20 shows an exemplary mounting member in accordance with one aspectof the disclosed technology;

FIG. 21 is a side view of the mounting member of FIG. 20;

FIG. 22 is an enlarged view of a portion of FIG. 21;

FIG. 23 shows an exemplary mounting member in accordance with one aspectof the disclosed technology;

FIG. 24 shows a central wire-way in accordance with one aspect of thedisclosed technology;

FIG. 25 shows a central wire-way cover plate in accordance with oneaspect of the disclosed technology;

FIG. 26 shows a frame wire compartment in accordance with one aspect ofthe disclosed technology;

FIG. 27 shows an exemplary knockout bracket in accordance with oneaspect of the disclosed technology;

FIG. 28 shows a bottom view of a light fixture includes a wirecompartment in accordance with one aspect of the disclosed technology;

FIG. 29 is an enlarged view of a portion of FIG. 28;

FIG. 30 shows an exploded view of an exemplary bottom frame assembly inaccordance with one aspect of the disclosed technology;

FIG. 31 is a bottom plan view of the bottom frame assembly of FIG. 30;

FIG. 32 is an enlarged view of an exemplary inside bracket shown in FIG.30;

FIG. 33 is an enlarged view of an exemplary divider shown in FIG. 30;

FIG. 34 shows an exploded view of an exemplary bottom frame assembly inaccordance with one aspect of the disclosed technology;

FIG. 35 shows an exploded view of an exemplary bottom frame assembly inaccordance with one aspect of the disclosed technology;

FIGS. 36-40 illustrate a retrofitting method in accordance with oneaspect of the disclosed technology;

FIG. 41 shows an exemplary electrical connector in accordance with oneaspect of the disclosed technology;

FIG. 42 shows an exemplary fluorescent socket;

FIG. 43 shows an exemplary fluorescent socket;

FIGS. 44-46 illustrate a retrofitting method in accordance with oneaspect of the disclosed technology;

FIG. 47 is a front perspective view of a desk lamp in accordance withone aspect of the disclosed technology;

FIG. 48 is a rear perspective view of a desk lamp in accordance with oneaspect of the disclosed technology;

FIG. 49 is a side view of a desk lamp in accordance with one aspect ofthe disclosed technology;

FIG. 50 is a front perspective view of a desk lamp in accordance withone aspect of the disclosed technology;

FIG. 51 is a rear perspective view of a desk lamp in accordance with oneaspect of the disclosed technology;

FIG. 52 is a side view of a desk lamp in accordance with one aspect ofthe disclosed technology;

FIG. 53 is a front view of a desk lamp in accordance with one aspect ofthe disclosed technology;

FIG. 54 is a side view of a desk lamp in a folded configuration inaccordance with one aspect of the disclosed technology; and

FIG. 55 is a side view of a desk lamp in a folded configuration inaccordance with one aspect of the disclosed technology.

DETAILED DESCRIPTION

To illustrate aspects of the disclosed technology in a clear and concisemanner, the drawings may not necessarily be to scale and certainfeatures may be shown in somewhat schematic form.

Existing lighting fixtures of commercial light systems cannot be easilyupgraded to replace obsolete lighting fixtures with lighting fixturesthat incorporate modern components, or refurbished with moderncomponents to reverse the effects of deterioration. Conventionalfluorescent lighting fixtures and available retrofitting kits areunsatisfactory for upgrading existing lighting systems because, amongother things, the existing lighting fixtures must first be removed or,at the least, significantly modified by removing certain components fromthe existing lighting fixtures before the upgrade can be performed.Retrofitting with conventional fluorescent luminaires or availableretrofitting kits is a labor-intensive and lengthy process thatsignificantly disrupts commercial operations during the retrofitprocess. Some retrofit kits are configured to employ light emittingdiodes (LEDs) utilized in replacement components, however, these kitsstill require more complex installation and/or provide less thandesirable light output.

The present disclosure recognizes shortcomings associated withconventional fluorescent lighting fixtures and conventional retrofitkits and provides an improved lighting fixture and associated retrofitkit including a substantially flat LED panel that can be formed in avariety of shapes and sizes. As is described more fully below, thesubstantially flat LED panel provides a low-thickness form factor thatsupports a variety of replacement, original installation and retrofitapplications. The provision of a substantially flat LED panel havingedge lighting allows for thin panels of flexible length and widthproviding uniform light output. The lighting fixture and associatedretrofit kit provides a device with great versatility and simplicity ofinstallation.

Referring now to FIGS. 1-9, an exemplary embodiment of a light fixture10 having a light emitting diode (LED) panel 12 is provided. In oneembodiment, the LED panel 12 is a substantially flat LED panel (alsoreferred to simply as a LED panel). The term “substantially flat LEDpanel,” as used in connection with the description of variousembodiments, is meant to include LED panels having a thickness that issubstantially less than the length and width of the panel. In addition,the term “substantially flat LED panel” is meant to include LED panelsof slightly non-uniform thickness, for example, LED panels that includeframes (designated generally as 14) having a thickness that is greaterthan the thickness of the light panel as well as LED light panels thatdo not include frames. As is discussed more fully below, the provisionof a light fixture and associated retrofit lighting kit having asubstantially flat LED panel provides for great versatility inapplication and simple installation in a variety of applications,including applications to retrofit existing fluorescent lighting units.

Viewing the substantially flat LED panel 12 from the front, the panel 12can be divided into a frame 14, and light emitting structures 30surrounded by the frame 14. The frame 14 provides structural support,contains components of the LED panel such as strips(s) of LEDs 30 andpower circuitry (designated generally as 16), and provides heatdissipation. It will be appreciated that power circuitry 16 can includeLED drivers, integrated power supplies, control circuitry, and the like.Generally, it is desirable for the frame 14 to be narrow, subject to thevarious requirements of the frame 14. In an embodiment of FIGS. 7-8,including externally mounted transformer block (16) with wiredconnection to LED strips 30, typical widths of the frame 14 are in therange of about 4 millimeters to about 10 millimeters, more preferablyabout 4 millimeters to about 8 millimeters. However, significantlynarrower frames may be employed in conjunction with compact componentssuch as microthin LED strips. Wider frames may also be used forfunctional or design considerations; for example the frame 14 of FIG. 6Aincludes wider segments to house relatively bulky driver circuitry 16.As another example, and as is described more fully below, the outerdimensions of the frame may be customized to fit within an enclosedspace, such as a cover of a fluorescent housing unit, or an insidecabinet lighting installation. The outer and interior edges of the framemay have the same shape (e.g. rectangles) or different shapes. The framemay have the same or substantially similar width on all sides, or mayhave different widths on different sides as in FIG. 6A.

The light fixture 10, including the substantially flat LED panel 12, maytake on a variety of dimensions and form factors, including, but notlimited to, rectangular, other polygonal (e.g. octagonal), circular andelliptical form factors. For example, the light fixture 10 can berectangular with a size of approximately two feet by four feet (2 feet×4feet), corresponding to an exemplary lower dimension of a standardfluorescent ceiling troffer. In another exemplary embodiment, the lightfixture 10 can have dimensions of about one foot by about four feet. Inyet another exemplary embodiment, the light fixture 10 can be sized tostandard lengths for under counter or under cabinet lightingapplications (12 inches, 18 inches, 24 inches, 36 inches, etc.). It willbe appreciated that the retrofitting method is not limited tofluorescent units of any particular size. The substantially flat LEDpanel 12 can take on any size without departing from the scope of thepresent invention. This versatility in sizing provides enhancedflexibility and use in connection with a variety of applications.

In accordance with one exemplary embodiment, the light fixture 10includes a frame 14, a substantially flat LED panel 12 disposed withinthe frame 14 and power circuitry (designated generally as 16 disposedwithin the frame 14 or adjacent the frame 14, where the power circuitry16 is configured to electrically couple the substantially flat LED panel12 to an external power supply (not shown). The substantially flat LEDpanel 12 can be configured to provide bright, uniform light in arelatively thin package. For example, in one embodiment, thesubstantially flat LED panel 12 has a thickness of less than about 1.0inches. In accordance with another embodiment, the substantially flatLED panel 12 has a thickness of less than about 0.5 inches.

FIGS. 8 and 9 show an exemplary embodiment in which the substantiallyflat LED panel includes a plurality of layers along with edge lightingdisposed adjacent to at least one edge of the frame. In the illustratedexemplary embodiment, the substantially flat LED panel includes anoptically-transmissive panel 20, e.g., a light guide plate or otherpolycarbonate or acrylic plate configured to produce even distributionof light received at edges of the optically-transmissive panel 20. Anarray of LEDs (designated generally as 30) can be disposed adjacent atleast one edge of the frame 14 and the optically transmissive panel 20.For example, a strip of LEDs 30 may be supported adjacent to one edge ofthe frame 14 (e.g., disposed within a channel in the frame) and adjacentto one edge of the optically-transmissive panel 20. Alternatively, thesubstantially flat LED panel 12 can include strips of LEDs 30incorporated into or at least partially supported by two edges of theframe 14. In yet another exemplary embodiment in which the light fixture10 has a rectangular form factor, the substantially flat LED panel 12can include strips of LEDs 30 incorporated into or at least partiallysupported by all four edges of the frame 14. The LEDs can be sized andpositioned such that the “emission dimension” of the LED elements hasthe same thickness or slightly less thickness than the thickness of thelight input edge of the optically-transmissive panel, thereby allowingfor an extremely thin profile.

The substantially flat LED panel 12 can include a diffuser film 22disposed on a first side of the optically-transmissive panel 20, e.g.,below the optically transmissive panel 20 when the fixture is mountedhorizontally for a ceiling lighting application. The outer diffuser film22 is configured to provide uniform light output, and can be made of anysuitable material. For example, for outdoor applications, the outerdiffuser film 22 can be a weatherable film. The outer diffuser film 22can be configured as a soft film or as a hard, abrasion-resistant filmdepending upon the particular application. The outer diffuser film 22can be made waterproof or moisture proof depending upon the desiredapplication.

The substantially flat LED panel 12 can include a brightness enhancementfilm (BEF) 24 disposed on a second side of the optically-transmissivepanel 20, e.g., above the optically transmissive panel 20 when thefixture is mounted horizontally for a ceiling lighting application. Thebrightness enhancement film 24 can be configured to collimate lightalong a vertical axis to improve the overall light output from thesubstantially flat LED panel 12. In accordance with one embodiment, thesubstantially flat LED panel can be configured to include multiple BEFsoptimized for the particular arrangement of LEDs along one or more edgesof the substantially flat LED panel. In this exemplary embodiment thesubstantially flat LED panel can include an optically transmissive panelin the form of a light guide plate with a first array of LEDsincorporated into a first side of the frame adjacent a first side of thelight guide plate, the first array of LEDs emitting light focused alonga first direction, and a second array of LEDs incorporated into a secondside of the frame adjacent a second side of the light guide plate, thesecond array of LEDs emitting light focused along a second directionthat is opposite the first direction. The substantially flat LED panelcan include a first brightness enhancement film (BEF) positionedadjacent the light guide plate and configured to collimate light emittedby the first array of LEDs, and a second BEF positioned adjacent thefirst BEF and configured to collimate light emitted by the second arrayof LEDs.

Turning back to FIG. 9, the substantially flat LED panel 12 can includea reflector 26 positioned on the other side of the BEF 24, e.g., abovethe BEF 24 when the fixture is mounted horizontally for a ceilinglighting application. The reflector 26 is configured and position toreturn a portion of the light emitted by the optically-transmissivepanel 20 in a direction opposite the intended output direction, therebyproviding enhanced total light output. In the illustrated exemplaryembodiment, the substantially flat LED panel 12 includes a backing 28,e.g., a sheet metal backing disposed adjacent the other side of thereflector 26. A sheet metal backing 28 in combination with a metallic(e.g. aluminum) frame (14) can provide excellent dissipation of heatgenerated by the LEDs.

The light fixture 10 includes power circuitry 16 disposed within theframe 14, adjacent the frame 14 or outside the frame 14, where the powercircuitry 16 is configured to electrically couple the substantially flatLED panel 12 to an external power source. In one exemplary embodiment,where the light fixture is employed in a retrofitting application for afluorescent ceiling light, the power circuitry 16 can include a blocktransformer configured to be electrically coupled directly to anexternal power supply, to the external power supply through a socketassociated with the fluorescent lighting unit (see, for example FIGS. 16and 17) or to a ballast associated with the fluorescent lighting unit.

In accordance with an alternative embodiment, the power circuitry caninclude an LED driver incorporated into a portion of the frame andconfigured to electrically couple the LEDs to an external power source.It will be appreciated that this embodiment serves to provide a lightfixture with an extremely thin form factor that can be easily mounted toa flat surface, such as a wall, an underside of a cabinet or the like.As shown in FIGS. 5 and 6, the light fixture 10 can be configured toinclude first and second LED strips 30 disposed on opposite sides of theframe 14, along with power circuitry in the form of a pair of LEDdrivers 16 positioned in one or both of the remaining sides of therectangular frame. The illustrated embodiment shows a first LED driver16 electrically coupled to and configured to control a first LED array(e.g., an LED strip 30), along with a second LED driver 16 coupled toand configured to control the second LED array (e.g., an LED strip).

FIG. 6A shows an alternative light fixture 10 with first and second LEDstrips 30 disposed on opposite sides of the frame 14 (e.g., on a topside of the frame and on a bottom side of the frame in the orientationprovided in FIG. 6), and with a pair of LED drivers 16 positioned onboth remaining sides of the frame. These remaining sides are wider thanthe sides containing of the LED strips, in order to house larger LEDdrivers (e.g. PCB-mounted transformers and other driver components).

As is discussed more fully below, it will be appreciated that it isdesirable to provide lighting kits well suited to a variety ofinstallations. Generally, in designing a flat LED panel, one shouldoptimize the optical stack and LEDs to satisfy optical requirements ofthe intended applications, having in mind anticipated form factor anddriver specifications of the flat LED panel. In providing a “universal”lighting kit, it is relatively easy to modify the frame design withoutchanging the core optical assembly, e.g. to provide different versionsof the lighting kit with minor variations in form factor or associatedcomponents.

The substantially flat LED panel can include a plurality of LEDs havingoutputs of various colors and/or color temperatures. For example, thesubstantially flat LED panel can include white LEDs having output of apredetermined color temperature. In accordance with another embodiment,the substantially flat LED panel can include a plurality of colored LEDs(e.g., LEDs having red output, green output and blue output), where thecolored LEDs are configured to cooperate to produce white light whenenergized. In the case of a plurality of colored LEDs, the light fixturecan include control circuitry that is configured to selectively energizethe colored LEDs to provide light output of variable color temperature.The control circuitry also can be configured to control the intensity ofthe light emitted by the substantially flat LED panel, thereby providinga dimming function.

In accordance with one embodiment, the substantially flat LED panelincludes one or more strips of LEDs disposed adjacent and least one edgeof the frame, where the strip of LEDs is removably coupled to the powercircuitry via a suitable electrical connector. It will be appreciatedthat this configuration allows for the easy replacement of one or morestrips of LEDs within the substantially flat LED panel. For example, inthe case of LED failure or burnout, the strip of LEDs could be easilyreplaced without replacing the entire fixture. In addition, the coloroutput of the light fixture could be altered by swapping out one or moreof the LED strips. For example, a holiday effect could be achieved byremoving a strip of white LEDs and replacing the strip of white LEDswith colored LEDs. To facilitate replacement of one or more LED stripswithin the flat LED panel, the frame can be provided with one or moresections that can be detached or otherwise separated from the remainderof the frame. For example, a cover section of the frame containing anLED strip may include a hinged connection to the remainder of the frame,and a pull tab. The user would pull open the cover section of the framein order to uncover the LED strip for replacement.

In accordance with one embodiment, the light fixture includes at leastone mounting member configured to mount (e.g., removably or permanentlymount) the frame to a support surface. It will be appreciated that themounting member may take on numerous forms depending on the desiredapplication. For example, the mounting member can be configured to mountthe frame to a substantially vertical support surface, such as a wall.In this case, the mounting member may include suitable clips, bracketsor the like configured to anchor the light fixture to a wall in a home,a wall in a hotel, a wall in a parking garage or the like. In anotherexemplary embodiment, the mounting member can be configured to mount theframe to a substantially horizontal support surface, such as a ceiling,the underside of a cabinet or the like. Examples of other applicationsinclude, but are not limited to, stairwell lighting, emergency lighting(optionally including a battery backup), task lighting for cubicles,under counter lighting (e.g., kitchen work areas and within chinacabinets), home or commercial garage lighting, lighting for retailshelving, aquarium lighting, and the like. As is described more fullybelow, the light fixture can be employed in a retrofit kit to retrofitan existing fluorescent lighting unit.

The mounting member can be tailored to the application. In applicationsin which it is anticipated that the flat LED panel will be removed as awhole for maintenance or replacement, a demountable mounting membershould be chosen. On the other hand, in applications in which the flatLED panel will not be normally removed as a whole, but may be maintainedby replacing components such as LED strips, a paramount considerationwould be physical security of the mounting. For example, in a flat LEDpanel retrofit kit designed for surface mounting to fluorescent ceilinglighting fixtures, one should use a secure mounting that satisfiesearthquake safety standards.

It will be appreciated that the light fixture can be arranged and/orinstalled together with a plurality of light fixtures where a primarylight fixture is electrically coupled to an external power supply andother light fixtures can be coupled to the external power supply by wayof the primary light fixture (so called “daisy chaining”).

Turning now to FIGS. 10-35, embodiments will be discussed in which thelight fixture 10 can be easily mounted to a flat surface, such as awall, a ceiling, such as in a parking garage, the underside of a cabinetor the like. While these features and embodiments are being discussed inconnection with mounting the light fixture to a flat surface, it will beappreciated that these features are equally applicable to retrofitapplications. In these embodiments, the power circuitry can beintegrated or otherwise disposed within a portion of the frame 14. Itshould be appreciated, however, that these embodiments also may beemployed together with an external power supply.

In accordance with one embodiment, which may be implemented togetherwith one or more of the other embodiments discussed in the presentapplication, the frame includes a bottom assembly 60 (also referred toas a bottom frame assembly, a bottom panel or a bottom panel assembly)and a top assembly 62 (also referred to as a top frame assembly, a toppanel or a top panel assembly) operatively coupled to the bottomassembly 60 (e.g., by suitable fasteners, such as screws, or by a snapfit). As is discussed more fully below, the bottom assembly 60 and thetop assembly 62 cooperate to form a plurality of channels within theframe. These channels can house or otherwise support power circuitry(including power supplies and associated driving circuitry), wiring, LEDarrays and the like.

As is discussed above, the frame 14, made up of the top assembly 62operatively coupled to the bottom assembly 60, can take on a variety ofform factors and dimensions without departing from the scope of thepresent invention. For example, the frame can be approximately two feetby approximately two feet (2 feet×2 feet), approximately one foot byapproximately two feet (1 foot×2 feet), approximately one foot byapproximately four feet (1 foot×4 feet), or the like.

The bottom assembly 60 is configured such that a central region of thebottom assembly is positioned over the rear of the optical components ofthe substantially flat LED panel 12. The bottom assembly 60 can includea bottom panel 62 configured to receive one or more brackets 66, 68within the inside edges of the bottom panel 62, thereby forming thebottom assembly 60.

For example, the exemplary embodiment illustrated in FIG. 10 shows apair of brackets 66 at two opposite edges of the bottom panel (e.g.,edges that house or otherwise support power supplies and/or drivingcircuitry). In the illustrated exemplary embodiment, the other twoopposite edges of the bottom assembly 60 include a pair of insidebrackets 68 configured to support LED strips or arrays. As will bediscussed more fully below, the bottom panel 62 can include or otherwisedefine two sets of slots configured to receive engagement members of anassociated mounting plate or other mounting structure.

FIG. 13 shows an exemplary embodiment of a first pair of inside brackets66. Each of the inside brackets 66 within the first pair of insidebrackets 66 can be configured to form the bottom an edge surface ofchannels that contain the power supplies at opposite edges of the frame.In the embodiment illustrated in FIG. 13, the narrower leg of theL-shaped inside bracket 66 is configured to separate the power supplycompartment from a central region at the rear of the lighting fixture. Acentral slot 70 provides an aperture through which AC input wires may berouted between the power supply compartment(s) and the central area ofthe frame assembly. For example, wires can be routed through this holeto a central wire-way (described more fully below). Cut away areas atthe ends of the inside brackets can be configured to provide aperturesthrough which DC-out wires from the power supply can be routed toconnect to LED strips on the other two edges of the frame.

FIG. 14 shows an exemplary embodiment of a second pair of insidebrackets 68. In the illustrated exemplary embodiment, each bracket 68 isconfigured to cooperate with the bottom panel 62 to hold an LED stripand mount the LED strip to one edge of the frame. The indented areas 72of each inside bracket allow for mounting the inside bracket to fit tothe side of the frame assembly. Engagement members at inner edges of thebottom panel can engage the indented areas 72 of each inside bracket 68.

In accordance with one or more embodiments, the bottom assembly 62 caninclude one or more mounting tabs 80. The mounting tabs 80 can beintegrally formed with a portion of the bottom assembly 60 (e.g., amovable or repositionable cut-out portion of the bottom assembly 60).Alternatively, the mounting tabs 80 can be operatively coupled to thebottom assembly 60. As shown in FIGS. 15-19, the mounting tabs 80 can beconfigured to be positioned in one of at least three positions: (1) anunextended, neutral or default position (FIG. 15), (2) a 90-degreeposition (bent or otherwise positioned at an angle of approximately 90degrees relative to a back surface of the bottom assembly) (FIG. 16 andFIG. 18) and (3) a 180-degree position (bent or otherwise positioned atan angle of approximately 180 degrees relative to a back surface of thebottom assembly) (FIG. 17 and FIG. 19).

The mounting tabs 80 can be rectangular in shape or can take on anotherconvenient shape. As can be seen in FIGS. 18-19, the mounting tabs 80include or otherwise define a mounting aperture 82 configured to accepta suitable fastener, such as a screw. It will be appreciated that themounting tabs 80 can be configured to cooperate with other fasteners,such as by securing wire hangers to the mounting tabs in their 90-degreeposition to provide a pendant lighting fixture. It also will beappreciated that the provision mounting tabs allows for mounting of thelight fixture against a flat surface without having mounting fastenerspenetrate the frame of the light fixture, such as by securing the lightfixture to a wall surface using screws inserted through the mountingtabs extending from the light fixture in their 180-degree position.

Alternatively, in embodiments in which the light fixture is mounted to asupport surface using another mechanism than the mounting tabs (such asretrofitting within a fluorescent housing unit), the mounting tabs maybe used to anchor the light fixture with wiring inserted through themounting aperture, in order to satisfy earthquake standards.

In accordance with another exemplary embodiment, which may beimplemented together with one or more of the other embodiments discussedin the present application, the light fixture can include or otherwisebe associated with a mounting member in the exemplary form of a mountingplate 90 for mounting the light fixture to a flat surface. It will beappreciated that the mounting plate will take on a size and form factorthat corresponds approximately to the size and form factor of the bottomassembly of the frame.

The mounting plate is configured to be secured or otherwise fastened toa mounting surface, such as a wall, ceiling or the underside of acabinet. For example, as shown in FIG. 20, the mounting plate includesor otherwise defines a number of mounting apertures 92 suitable forreceiving appropriate fasteners, such as screws. The mounting plate 90is configured to cooperate with and releasably engage the bottomassembly 60 (e.g., using a slide-lock mechanism) for mounting thelighting fixture to a flat surface. For example, as shown in FIGS.20-22, the mounting plate 90 can include a plurality of engagementmembers 94 (e.g., J-hooks in pairs at opposite edges of the mountingplates). These engagement members 94 can be configured to engage a setof slots at the outer edges of the bottom panel (e.g., via a slide-lockrelationship). A user may mount the light fixture to a surface using themounting plate by first securing the mounting plate to the surface, thenengaging the light fixture against the mounting plate.

The mounting plate 90 can be configured to include a central aperture 96to provide a central wiring entry point. The central aperture 96 can besized and configured to abut against an exterior junction box (e.g., analready-existing exterior junction box in a ceiling). In accordance withone embodiment, the mounting plate 90 can serve as a cover at the rearsurface of the light fixture.

It will be appreciated that the mounting member may take on other forms.For example, as shown in FIG. 23, the mounting member 98 can be in theform of a multi-piece structure. The mounting member can includeengagement members, such as those discussed above. The mounting member98 also defines a central aperture like the mounting member describedabove with respect to FIG. 21. It will be appreciated that thisconfiguration can provide a more flexible and lighter-weight mountingoption. Other mounting member configurations can be employed withoutdeparting from the scope of the disclosed technology.

It will be appreciated that the provision of a mounting member likethose described with respect to FIGS. 20-23 allows for acosmetically-superior surface mounting in that the mounting mechanismwill not be visible to the user when the light fixture is mounted.

Turning now to FIGS. 24-25, in accordance with another exemplaryembodiment, which may be implemented together with one or more of theother embodiments discussed in the present application, the bottomassembly can be configured to include a central wire-way (designatedgenerally as 100) (also see FIG. 11. The central wire-way 100 isconfigured to provide a location to receive and attach AC input wires,as well as to act as a wire-way channel for routing AC input wires to(and in the case of multiple power supplies, between) a single powersupply or multiple power supplies at opposite ends of the centralwire-way 100.

The central wire-way 100 can be formed by a protective cover 102operatively coupled to a back surface of the bottom assembly. Inaccordance with one embodiment, the central wire-way 100 includes orotherwise defines a central aperture 104, such as a knock-out hole,configured to receive AC input wiring electrically coupled to anexternal AC source. In accordance with another embodiment, the centralwire-way 100 may be provided without a central aperture.

The protective cover 102 can cooperate with the back surface of thebottom assembly to provide a channel to route wiring to or from edges ofthe frame. For example, a set of AC wires (ground and power) can runthrough the central wire-way to a power supply at one edge of the frame.In an embodiment in which there are two power supplies at opposite edgesof the frame, another set of AC wires can be routed back from that powersupply in the opposite direction to provide AC power to the second powersupply at the opposite edge of the frame. It will be appreciated thatthis AC-input wiring arrangement provides design flexibility as it iscompatible with light fixture configurations having either a powersupply at one edge, or at two opposite edges, of the frame.

In an alternative embodiment, AC wiring within the central wire-way caninclude a splitter. This would provide two sets of AC power wires thancould be routed in both directions from the central aperture to provideAC power to both power supplies without requiring additional wiringbetween the power supplies.

The central wire-way 100 can include a ground screw 106 to the side ofthe central aperture 104 to ground AC wires routed through the centralwire-way.

Turning now to FIGS. 26-31, in accordance with another exemplaryembodiment, which may be combined with one or more of the embodimentsdiscussed in the present application, the frame 14 is configured toinclude a wire compartment 110, which receives AC wiring at an edge ofthe frame. The wire compartment 110 can include a shell or otherprotective structure sized to fit within a portion of the frame. Aportion of the back surface of the bottom assembly of the frame candefine an aperture 112 approximately corresponding in size and shape tothe wire compartment 110 (also referred to as an access aperture). Thewire compartment 110 can include a cover (also referred to as a knockoutbracket) 114 having a knockout hole (also referred to as a knockoutaperture) 116 or other aperture for receiving AC power from an externalsource.

It will be appreciated that the frame can be configured to include acentral wire-way (without a central aperture) to route wiring to or fromother edges of the frame.

The knockout bracket 114 provides access to the wire compartment 110,acting like the cover of a junction box in providing an input point forAC cabling exterior to the wiring compartment 110. An example of ACconduit that can be coupled to the light fixture via the knockoutbracket is the commonly-used non-metallic sheathed cable supplied usingthe trade designation Romex™. This type of cable can be secured withinthe knockout of the knockout bracket using a knockout nut. The knockoutbracket 114 can include a grounding screw adjacent the knockout aperture116.

In accordance with one exemplary embodiment, the knockout bracket 114can be secured within the access aperture at one end by a downwardlyoffset flange 118, and at the other end by downwardly offset forks 120,including an apertured tab 122 between the forks and substantiallycoplanar with the main body of the bracket. In accordance with anexemplary embodiment, to insert the knockout bracket 114 within the cutout (access aperture) at the edge of the bottom panel, the user caninsert the flange 118 under the back panel of the flat light adjacentone side of the access aperture; pivot the other end of the bracket intothe access aperture cutout; and then slide the forked end 120 of theknockout bracket under the other end of the access aperture cutout, withthe aperture tab 122 resting above the panel's edge surface. Theknockout bracket 114 then can be secured to the bottom panel assemblyusing a screw at the aperture tab.

It will be appreciated that the knockout bracket provides a sturdystructure to cover and protect the wiring compartment, and to supportthe exterior cable as well as AC wiring within the compartment. Theknockout bracket can be made of material similar to the material used inthe covers of junction boxes, or of any other suitable material.

The central wire-way 100 of FIGS. 24-25 and the edge wire compartment110 of FIGS. 26-29 provide design options for receiving AC-input wiringand routing the wiring to a power supply within the light fixture. Forexample, the central wire way can be configured to receive and route 16gauge wiring or 18 gauge wiring according to the AWG (American WireGauge) system. This wiring has a nominal diameter in the range0.102-0.129 cm, and is rated with an ampacity (ampere capacity for safecurrent flow) of 10-13 amps, suitable for residential electric powerinstallations, for example the 120 Volts AC service used in NorthAmerica. As another example, the edge wire compartment with its sturdy,junction box-like configuration, may receive heavier, 12 gauge wiring(AWG), with a nominal diameter on the order of 0.205 cm and a ratedampacity of 23 amps. This wiring is often used in commercial electricpower installations, for example the 277 Volts AC service that is commonin commercial and industrial lighting in North America.

In accordance with an exemplary embodiment shown in FIGS. 30-33, whichmay be combined with one or more other embodiments described in thisapplication, the bottom assembly 130 can include, at the two channelsfor the power supply (defined at least partially by inside bracket 132and the bottom panel 136), an inside channel divider 134 than dividesthe channel within one edge of the frame between a compartment for apower supply, and a compartment for the AC-input wiring, isolating thesetwo compartments from one another. In accordance with one embodiment,the divider 134 is located off center within one edge of the frame toprovide a longer compartment for the power supply that for the wirecompartment.

In this exemplary embodiment, the inside bracket 132 forms an insidechannel or shell, which constrains the wiring within the wirecompartment, and secures the wire compartment and power supplycompartment from exterior forces. The shell can include a slot at itsinner wall surface to permit AC wiring to pass from the shell to thecentral wire-way.

While the above features have been described with respect to anexemplary frame dimension of two feet by two feet, it will beappreciated that similar configurations can be used for other dimensionsand form factors, such as one foot by one foot, one foot by two feet,one foot by four feet, and the like. For example, FIG. 34 shows anexemplary bottom assembly for a one foot by two feet light fixture. Thefeatures of this frame assembly are generally the same as theabove-described features of the two feet by two feet embodiment, exceptfor dimensions. In this exemplary embodiment, the LED strips aredeployed along the longer edges of the frame, while the power suppliesare deployed along the shorter edges of the frame.

FIG. 35, shows the bottom assembly for an exemplary one foot by 4 feetlight fixture. In this exemplary embodiment, there are no components atthe shorter edges of the bottom panel. The edge brackets at these edgesserve only as a structural barrier for the substantially flat LED panel.In this exemplary embodiment, one of the long-dimension edge areas iswider than the opposite long-dimension edge area because one of the edgeareas supports two power supplies, while the other edge area supports apair of LED strips.

As is discussed above, the substantially flat LED panel can beincorporated into a number of applications. For example, turning now toFIGS. 36-46, a retrofit lighting kit and a method of retrofitting afluorescent housing unit, e.g., a fluorescent ceiling light fixture(“troffers”), will be described. It will be appreciated that theretrofit lighting kit is versatile. For example, it can be employed inconnection with standard diffuser troffers (see, e.g., FIG. 36) as wellas in connection with aluminized reflector troffers.

For purposes of discussion, the fluorescent lighting unit to be retrofitwill be understood to include a housing unit, one or more fluorescentsockets and a ballast disposed within the housing unit. Also, forpurposes of explanation, the fluorescent housing unit to be retrofitincludes an upper extent or upper portion and a lower extent or lowerportion. The lower extent of the fluorescent housing unit includes aperimeter of a given shape and size. For example, the perimeter can beapproximately two feet by four feet (2 feet×4 feet), as can be found ina standard fluorescent ceiling troffer. In another exemplary embodiment,the perimeter can be one foot by four feet. In yet another exemplaryembodiment, the perimeter can be four feet by four feet. It will beappreciated that the retrofitting method is not limited to fluorescentunits of any particular size. The substantially flat LED panel can takeon any size without departing from the scope of the present invention.

It will be appreciated that while the retrofit kit and method are beingdescribed with respect to troffers of different geometries andconfigurations, a preferred embodiment of the retrofit kit will includeappropriate hardware for mounting the retrofit kit to a variety ofdifferent troffers, effectively providing a “universal” mounting kit.

The lighting kit (also referred to as a retrofit kit) can include asubstantially flat light emitting diode (LED) panel having a shape andsize of approximately the given shape and size of the perimeter of thelower extent of the housing unit, power circuitry configured toelectrically couple the substantially flat LED panel to a power supply,and at least one engagement member configured to couple thesubstantially flat LED panel to the housing unit of the fluorescentlighting unit.

The substantially flat LED panel can employ one or more of the featuresdescribed above. The substantially flat LED panel can include a framehaving a shape and size of approximately the given shape and size of theperimeter of the lower extent of the fluorescent housing unit. As isdiscussed above, the substantially flat LED panel can include a frame aswell as a plurality of layers along with edge lighting disposed adjacentto at least one edge of the frame. For example, the substantially flatLED panel can include an optically-transmissive panel, an array of LEDsdisposed adjacent at least one edge of the frame and the opticallytransmissive panel, a diffuser film disposed below theoptically-transmissive panel; a brightness enhancement film (BEF)disposed above the optically-transmissive panel, and a reflectordisposed above the BEF.

The substantially flat LED panel can include an optically-transmissivepanel, e.g., a light guide plate or other polycarbonate or acrylic plateconfigured to produce even distribution of light received at edges ofthe optically-transmissive panel. An array of LEDs can be disposedadjacent at least one edge of the frame and the optically transmissivepanel. For example, a strip of LEDs may be supported adjacent to oneedge of the frame (e.g., disposed within a channel in the frame) andadjacent to one edge of the optically-transmissive panel. Alternatively,the substantially flat LED panel can include strips of LEDs incorporatedinto or at least partially supported by two edges of the frame. In yetanother exemplary embodiment in which the light fixture has arectangular form factor, the substantially flat LED panel can includestrips of LEDs incorporated into or at least partially supported by allfour edges of the frame. The LEDs can be sized positioned such that the“emission dimension” of the LED elements has the same thickness orslightly less thickness than the thickness of the light input edge ofthe optically-transmissive panel, thereby allowing for an extremely thinprofile.

In accordance with one embodiment, the at least one engagement member isconfigured to couple the substantially flat LED panel over the perimeterof the housing unit. For example, the retrofit kit can include clamps tofacilitate snap-on mounting over the perimeter of the housing unit.

In accordance with another embodiment, the at least one engagementmember is configured to couple the substantially flat LED panel withinthe perimeter of the lower extent of the housing unit. For example, theretrofit kit can include appropriate tension clamps or fold down clampsto facilitate mounting within the perimeter of the lower extent of thehousing unit. Alternatively, the frame of the substantially flat LEDpanel can be sized to snap into the perimeter of the lower extent of thehousing unit without use of additional securement, such as clamps. Inthis embodiment, the perimeter of the lower extent of housing unit caninclude a channel having a thickness, with the substantially flat LEDpanel having a thickness approximately equal to the thickness of thechannel around the perimeter of the lower extent of the fluorescenthousing unit.

In one embodiment, the at least one engagement member is configured tohingedly mount the substantially flat LED panel to the lower extent ofthe housing unit. In another embodiment, the housing unit can include acover hingedly connected to a body, and the at least one engagementmember can be configured to couple the substantially flat LED panel tothe cover such that the substantially flat LED panel is hingedly mountedto the body of the fluorescent housing unit via the cover. In thisembodiment, the cover can define a channel around a perimeter of thecover, the channel having a thickness, wherein the substantially flatLED panel has a thickness approximately equal to the thickness of thechannel around the perimeter of the cover.

In accordance with another exemplary embodiment, the fluorescentlighting unit can include a reflector grid connected to the housingunit, wherein engagement member is configured to couple thesubstantially flat LED panel over the reflector grid. Alternatively, thefluorescent lighting unit can include a reflector grid connected to thehousing unit, wherein engagement member is configured to couple thesubstantially flat LED panel to the housing unit above the reflectorgrid.

The lighting kit can further include power circuitry in the form of ablock transformer. As is described more fully below, the blocktransformer can electrically couple the substantially flat LED panel tothe power supply associated with the fluorescent lighting unit bybypassing the ballast associated with the fluorescent housing unit.Alternatively, the power circuitry can be configured to electricallycouple the substantially flat LED panel to the ballast associated withthe fluorescent lighting unit. In accordance with another embodiment,the power circuitry includes a transformer incorporated into the frameof the substantially flat LED panel.

In one embodiment, the power circuitry can include at least oneelectrical connector configured to electrically connect thesubstantially flat LED panel to at least one fluorescent socket. Forexample, the electrical connector can be configured to include a pair ofprongs configured to snap into the fluorescent socket (see, e.g., FIGS.41 and 42). Alternatively, the electrical connector can be configured tocouple to a fluorescent socket where the connector is inserted andturned to lock into place (see, e.g., FIG. 43).

The retrofit lighting kit described above can be employed in connectionwith a method of retrofitting a fluorescent housing unit (e.g., atroffer) having an upper extent and a lower extent, where the lowerextent has a perimeter of a given shape and size. The retrofittingmethod can include providing a substantially flat light emitting diode(LED) panel, the substantially flat LED panel having a shape and size ofapproximately the given shape and size of the perimeter of the lowerextent of the fluorescent housing unit. The substantially flat LED panelcan be electrically coupled to a power supply associated with thefluorescent housing unit, and the substantially flat LED panel can bemounted to the fluorescent housing unit.

As is described above, the substantially flat LED panel includes a framehaving a shape and size of approximately the given shape and size of theperimeter of the lower extent of the fluorescent housing unit and thesubstantially flat LED panel can be mounted over the perimeter of thefluorescent housing unit (e.g., using suitable clamps, such as fold downclamps or tensioner clamps). Alternatively, the mounting step caninclude mounting the substantially flat LED panel within the perimeterof the lower extent of the fluorescent housing unit. In this embodiment,the perimeter of the lower extent of fluorescent housing unit caninclude a channel having a thickness, with the substantially flat LEDpanel having a thickness approximately equal to the thickness of thechannel around the perimeter of the lower extent of the fluorescenthousing unit.

In an alternative embodiment where the fluorescent housing unit includesa cover hingedly connected to a body, the cover including a diffuserand/or a lens (see, for example, FIGS. 36-40), mounting can includeremoving the diffuser and/or lens from the cover and mounting thesubstantially flat LED panel to the cover, such that the substantiallyflat LED panel is hingedly mounted to the body of the fluorescenthousing unit via the cover. In this embodiment, the cover can define achannel around a perimeter of the cover, the channel having a thickness,wherein the substantially flat LED panel has a thickness approximatelyequal to the thickness of the channel around the perimeter of the cover.

In a case where the fluorescent housing unit includes a reflector gridconnected to a body, the step of mounting can include removing thereflector grid and mounting the substantially flat LED panel to thelower extent of the body of the fluorescent housing unit. Alternatively,mounting can include removing the reflector grid and mounting thesubstantially flat LED panel to the body of the fluorescent housing unitand replacing the reflector grid such that the substantially flat LEDpanel is positioned above the reflector grid.

The step of electrically coupling the substantially flat LED panel to apower supply associated with the fluorescent housing unit can beaccomplished in a number of ways. For example, electrically coupling caninclude removing a ballast associated with the fluorescent housing unitand electrically coupling the substantially flat LED panel to the powersupply via a block transformer. Alternatively, electrically coupling caninclude electrically coupling the substantially flat LED panel to thepower supply via one or more fluorescent light sockets associated withthe fluorescent housing unit (e.g., where the substantially flat LEDpanel includes one or more connectors configured to electrically connectwith the fluorescent light sockets associated with the fluorescenthousing unit). In accordance with yet another embodiment, electricallycoupling can include electrically coupling the substantially flat LEDpanel to a ballast associated with the fluorescent housing unit (e.g.,via an external block transformer associated with the LED panel or via atransformer or other LED driver incorporated into the frame of thesubstantially flat LED panel).

Turning now to FIGS. 47-55, another exemplary embodiment of thedisclosed technology is provided. In accordance with this exemplaryembodiment, the substantially flat LED panel described above can beincorporated into a desk lamp (50). The desk lamp (50) can include abase (52), at least one support (54) coupled to the base (52) and asubstantially flat LED panel (56) operatively coupled to the at leastone support (54). In the illustrated embodiment of FIGS. 47-50, the desklamp (50) includes a rectangular base (52) operatively coupled to a pairof supports (54) extending upward from the rectangular base (52). Thesupports (54) are operatively coupled to the substantially flat LEDpanel (56) (e.g., by a hinge mechanism (58) that allows thesubstantially flat LED panel (56) to rotate relative to the supports(54)).

In the illustrated embodiment, the substantially flat LED panel (56) hasa generally square form factor (e.g., a square of about six inches byabout six inches), however, the substantially flat LED panel (56) maytake on a variety of form factors and sizes without departing from thescope of the disclosed technology. For example, the substantially flatLED panel (56) may be rectangular, circular, elliptical, or the like. Inaddition, the base (52) may take on a variety of geometries, such as therectangular base illustrated in FIGS. 47-50 or the substantiallycircular base illustrated in FIGS. 50-53. The supports (54) may befixedly coupled to the base or, as is described more fully below, thesupports (54) may be rotationally coupled to the base (52) allowing forgreater adjustment as well as secure and efficient packaging of the desklamp.

In accordance with one exemplary embodiment, the desk lamp can includeLED drive circuitry operatively coupled to the substantially flat LEDpanel. The LED drive circuitry may be housed or otherwise supportedwithin the base. Alternatively, the LED drive circuitry may be housed orotherwise supported within a frame associated with the substantiallyflat LED panel.

The substantially flat LED panel can employ one or more of the featuresdiscussed above with respect to FIGS. 1-9. For example, thesubstantially flat LED panel can include a frame and a plurality of LEDspositioned about at least a portion of the frame. In the case of asquare or rectangular frame, the plurality of LEDs can be positionedalong one side of the frame or more than one side of the frame. In thecase of a round or elliptical frame, the plurality of LEDs can bedisposed along at least a portion of the circumference or perimeter ofthe frame.

In accordance with one embodiment, the substantially flat LED panelincludes an optically-transmissive panel, a frame surrounding theoptically-transmissive panel, an array of LEDs disposed adjacent atleast one edge of the frame and the optically transmissive panel, adiffuser film disposed below the optically-transmissive panel, abrightness enhancement film (BEF) disposed above theoptically-transmissive panel, and a reflector disposed above the BEF. Inone embodiment, the substantially flat LED panel can have a thicknessless than about 1.0 inches. In another embodiment, the substantiallyflat LED panel can have a thickness of less than about 0.5 inches.

Also, as discussed above with respect to FIGS. 1-9, the substantiallyflat LED panel can include a plurality of LEDs having outputs of variouscolors and/or color temperatures. For example, the substantially flatLED panel can include white LEDs having output of a predetermined colortemperature. In accordance with another embodiment, the substantiallyflat LED panel can include a plurality of colored LEDs (e.g., LEDshaving red output, green output and blue output), where the colored LEDsare configured to cooperate to produce white light when energized. Inthe case of a plurality of colored LEDs, the desk lamp can include LEDdriver circuitry that is configured to selectively energize the coloredLEDs to provide light output of variable color temperature. The controlcircuitry also can be configured to control the intensity of the lightemitted by the substantially flat LED panel, thereby providing a dimmingfunction.

In accordance with one embodiment, the substantially flat LED panel caninclude one or more strips of LEDs disposed adjacent and least one edgeof the frame, where each strip of LEDs is removably coupled to the powercircuitry via a suitable electrical connector. It will be appreciatedthat this configuration allows for the easy replacement of one or morestrips of LEDs within the substantially flat LED panel. For example, inthe case of LED failure or burnout, the strip of LEDs could be easilyreplaced without replacing the entire substantially flat LED panel. Inaddition, the color output of the desk lamp could be altered by swappingout one or more of the LED strips.

Turning now to FIGS. 54-55, an embodiment where the substantially flatLED panel (56) is hingedly coupled to a pair of supports (54) (e.g., bya hinge mechanism (58)), which are hingedly coupled to the base isillustrated. As can be seen, this embodiment allows for efficient andsecure packaging, storage, and/or transportation of the desk lampbecause the desk lamp can be folded into a relatively flatconfiguration.

As is discussed above, the provision of a light fixture making use of asubstantially flat LED panel provides for great versatility inapplications ranging from a standalone lighting unit, to a retrofitlighting kit to a desk lamp. Examples of other applications include, butare not limited to, stairwell lighting, emergency lighting (optionallyincluding a battery backup), task lighting for cubicles, under counterlighting (e.g., kitchen work areas and within china cabinets), home orcommercial garage lighting, lighting for retail shelving, aquariumlighting, and the like. The provision of a substantially flat LED panelhaving edge lighting allows for thin panels of flexible length and widthproviding uniform light output.

Although the invention has been shown and described with respect to acertain embodiment or embodiments, it is obvious that equivalentalterations and modifications will occur to others skilled in the artupon the reading and understanding of this specification and the annexeddrawings. In particular regard to the various functions performed by theabove described elements (components, assemblies, devices, compositions,etc.), the terms (including a reference to a “means”) used to describesuch elements are intended to correspond, unless otherwise indicated, toany element which performs the specified function of the describedelement (i.e., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure which performs thefunction in the herein illustrated exemplary embodiment or embodimentsof the invention. In addition, while a particular feature of theinvention may have been described above with respect to only one or moreof several illustrated embodiments, such feature may be combined withone or more other features of the other embodiments, as may be desiredand advantageous for any given or particular application.

1.-58. (canceled)
 59. A light fixture comprising: a frame; asubstantially flat light emitting diode (LED) panel disposed within theframe; and power circuitry disposed within the frame or adjacent theframe, the power circuitry being configured to electrically couple thesubstantially flat LED panel to an external power supply.
 60. The lightfixture of claim 59, wherein the substantially flat LED panel includes aplurality of LEDs disposed adjacent at least one edge of the frame. 61.The light fixture of claim 59, wherein the frame is rectangular and thesubstantially flat LED panel includes an array of LEDs incorporated intoat least two sides of the frame.
 62. The light fixture of claim 59,wherein the substantially flat LED panel includes: anoptically-transmissive panel; an array of LEDs disposed adjacent atleast one edge of the frame and the optically transmissive panel; adiffuser film disposed above the optically-transmissive panel; abrightness enhancement film (BEF) disposed below theoptically-transmissive panel; and a reflector disposed below the BEF.63. The light fixture of claim 59, wherein the frame of the lightfixture has a thickness of less than about 0.5 inches. 64.-72.(canceled)
 73. The light fixture of claim 59, wherein the frame isrectangular and the substantially flat LED panel includes: a light guideplate; a first array of LEDs incorporated into a first side of the frameadjacent a first side of the light guide plate, the first array of LEDsemitting light focused along a first direction; a second array of LEDsincorporated into a second side of the frame adjacent a second side ofthe light guide plate, the second array of LEDs emitting light focusedalong a second direction that is opposite the first direction; a firstbrightness enhancement film (BEF) positioned adjacent the light guideplate and configured to collimate light emitted by the first array ofLEDs; and a second BEF positioned adjacent the first BEF and configuredto collimate light emitted by the second array of LEDs.
 74. The lightfixture of claim 59, wherein the substantially flat LED panel includes astrip of LEDs disposed adjacent at least one edge of the frame, thestrip of LEDs being removably coupled to the power circuitry via anelectrical connector.
 75. The light fixture of claim 59, wherein thepower circuitry comprises a transformer.
 76. The light fixture of claim59, wherein the power circuitry comprises a LED driver disposed withinthe frame.
 77. The light fixture of claim 59, wherein the powercircuitry comprises a controller configured to control the intensity ofthe light emitted by the substantially flat LED panel.
 78. The lightfixture of claim 59, wherein the frame includes a bottom assembly and atop assembly coupled to the bottom assembly, the bottom assembly and thetop assembly cooperating to form a plurality of channels within theframe.
 79. The light fixture of claim 78, wherein the bottom assemblyincludes a back surface and a plurality of mounting tabs on the backsurface, wherein the mounting tabs are movable between (i) a firstunextended position where the mounting tabs are substantially co-planarwith the back surface, (ii) a first extended position where the mountingtabs extend out at an angle of approximately 90 degrees relative to theback surface, and (ii) a second extended position where the mountingtabs extend out at an angle of approximately 180 degrees relative to theback surface.
 80. The light fixture of claim 79, wherein the mountingtabs are integrally formed with the back surface of the bottom assembly.81. The light fixture of claim 79, wherein the mounting tabs are formedas a cut-out from the back surface of the bottom assembly.
 82. The lightfixture of claim 79, wherein the mounting tabs are operatively coupledto the back surface of the bottom assembly.
 83. The light fixture ofclaim 79, wherein the mounting tabs define an aperture configured toreceive a fastener.
 84. The light fixture of claim 79, wherein themounting tabs are configured to remain in position when moved to thefirst extended position or when moved to the second extended position.85. The light fixture of claim 78, further comprising: a mounting plateconfigured to be attached to a flat surface, wherein the mounting plateincludes a plurality of engagement members configured to engage thebottom assembly of the frame.
 86. The light fixture of claim 85, whereinthe engagement members comprise a plurality of J-hooks configured toengage slots within outer edges of the bottom assembly.
 87. The lightfixture of claim 85, wherein the mounting plate is configured toreleasably engage the bottom assembly of the frame through a slide-lockmechanism.
 88. The light fixture of claim 85, wherein the mounting platedefines a central aperture configured to cooperate with an externaljunction box.
 89. The light fixture of claim 85, wherein the mountingplate defines a central aperture configured to receive AC input wiring.90. The light fixture of claim 78, wherein the power circuitry isdisposed within at least one of the plurality of channels within theframe, the power circuitry being configured to electrically couple thesubstantially flat LED panel to an external AC power supply; and thelight fixture including a central wire-way disposed adjacent a backsurface of the bottom assembly, wherein the central wire-way isconfigured to house wiring electrically coupled to the external AC powersupply.
 91. The light fixture of claim 90, wherein the central wire-wayis configured to route wiring between opposite edges of the frame. 92.The light fixture of claim 90, wherein the central wire-way isconfigured to route wiring electrically coupling the external AC powersupply to power supplies disposed within channels in opposite edges ofthe frame.
 93. The light fixture of claim 90, wherein the centralwire-way includes a back cover coupled to a back surface of the bottomassembly.
 94. The light fixture of claim 93, wherein the back coverdefines a central aperture configured to receive AC input wiringelectrically coupled to the external AC power supply.
 95. The lightfixture of claim 94, wherein the central aperture is configured as aknockout hole.
 96. The light fixture of claim 78, wherein the powercircuitry is disposed within at least one of the plurality of channelswithin the frame, the power circuitry being configured to electricallycouple the substantially flat LED panel to an external AC power supply;and the light fixture including a wire compartment disposed within atleast one of the plurality of channels within the frame, wherein thewire compartment is configured to house wiring electrically coupled tothe external AC power supply.
 97. The light fixture of claim 96, whereinthe bottom assembly of the frame defines an aperture configured toreceive AC input wiring from the external AC power supply.
 98. The lightfixture of claim 97, further comprising a protective shell for wiring inthe wire compartment, positioned within said at least one of theplurality of channels within the frame.
 99. The light fixture of claim98, wherein the aperture is configured as a knockout hole.
 100. Thelight fixture of claim 96, wherein at least one edge of the framedefines the wire compartment and a power supply compartment separatefrom the wire compartment.
 101. The light fixture of claim 96, furthercomprising a central wire-way disposed adjacent a back surface of thebottom assembly, wherein the central wire-way is configured to routewiring from the wire compartment in one edge of the frame to theopposite edge of the frame.
 102. (canceled)
 103. A lighting assemblycomprising the lighting fixture of claim 59 electrically coupled to asecond light fixture, the second light fixture comprising a frame and asubstantially flat light emitting diode (LED) panel disposed within theframe, wherein the second light fixture is electrically coupled to thelight fixture of claim 59 and configured to receive power from theexternal power supply associated with the light fixture of claim 59.104.-127. (canceled)